1. Field of the Invention
The present invention relates to a device for inducing and increasing the flow of heavy crude oil or viscous fluids into a centrifugal pump locate down-hole in an oil well. More specifically, the present invention attaches to the shaft of a centrifugal pump between the centrifugal pump and the gas separator. The invention serves to compress the residual gas that remains in the heavy crude oil after the oil has been degassed through a gas separator and forces the heavy crude oil into a centrifugal pump.
2. Description of the Related Art
When pumping oil wells that contain viscous crude oil with centrifugal pumps, the oil causes problems for the traditional down-hole degassing and pumping equipment. The viscosity of the oil prevents adequate release of residual gas upward within the well through the casing external to the pump and shaft. Because of the inadequate removal of the gas from the crude oil in the gas separator, the fluid that enters at the bottom of the centrifugal pump contains significant quantities of gas. As the fluid enters the lower two or three stages of a centrifugal pump, the fluid enters a low pressure or partial vacuum area formed by the normal spinning action of the pump. This partial vacuum or low-pressure area allows the residual gas that remains in the oil to be release, forming bubbles of gas within the heavy oil. This gas accumulates at the eye of the impeller in the low-pressure area of the pump since the impeller of the pump tends to sling the oil outward and upward within the stages of the pump. The presence of this free gas hampers the operation of the pump, causing it to operate much less efficiently, or causing the pump to gas lock.
The conventional method for addressing this problem is to use a larger pump and motor. The increased motor and pump size translates into higher electric operating costs and increased equipment costs per unit of oil pumped to the wellhead.
The current invention addresses this problem in a new way. The present invention is installed in the down-hole equipment string between the gas separator and the centrifugal pump. The invention serves to produce a continual positive pressure of fluids at the inlet of the centrifugal pump, thus causing the residual gases contained within the oil to remain dissolved as the oil enters the pump.
The invention consists of an auger that rotates within a housing. The rotating auger engages the fluid upon the fluid leaving the gas separator. The rotating auger positively pushes and lifts the fluid upward toward the bottom of the pump. As the fluid is moved upward within the housing by the auger, the residual gas is forced back into the fluid. When the fluid exits the top end of the invention and enters the lower end of the pump, the fluid is under pressure, instead of being under a vacuum. This allows the fluid to be induced into the lower stages of the pump by the normal rotational action of the pump with reduced interference from free gas.
By employing the present invention, the size of the pump motor can be reduced by approximately one half, thus decreasing the initial installation cost of the motor. More importantly, however, the present invention allows the pump to operate much more efficiently. Increased efficiency reduces the ongoing operational costs, i.e. the cost of electricity to operate the pump. This type of reduction in operational costs translates into savings of hundreds of dollars over the life of an oil well.